1. Field of the Invention
The present invention relates to an ink drying prevention apparatus, an ink-jet recording head storage container and an ink-jet recording apparatus that are provided therewith, and an ink drying prevention method.
2. Description of the Related Art
Conventionally, an ink-jet printer has been performing printing in a manner that jets ink from plural orifices formed on a nozzle plate of a jet nozzle and deposits the ink on a medium. If the above printer has been kept from printing for a long period of time, dry ink may cause the orifices to be clogged and dust may be deposited on the nozzle plate, so that a dot dropout may occur during printing, reducing printing quality or disabling printing. Accordingly, when recording will not be performed for a long period of time, when recording is to be performed with ink of a different color, or when a recording method is to be changed, the recording head is moved to a predetermined place within the ink-jet printer so that a drying prevention unit is activated to bring the printer to a stop, or the recording head having been used is removed from the ink-jet printer and housed in a storage container provided with a drying prevention unit.
As the above drying prevention unit, there is known one that a chamber corresponding to a jet nozzle is formed at the bottom and a rubber cap is disposed in the circumference of the chamber. By setting the recording head in the drying prevention unit with the jet nozzle facing the bottom, or by the recording head being slightly moved toward the drying prevention unit when the recording head is set in the drying prevention unit, the nozzle plate of the jet nozzle of the recording head is pressed against the cap, so that ink within the orifices is prevented from evaporating.
Conventionally, a variety of drying prevention units employing a cap are known. For example, caps used in the closed cap system are shaped so that they have no openings in other than portions abutting on a nozzle plate. Therefore, if a recording head is set in a drying prevention unit using a cap, since the chamber can be sealed, it can be prevented that dry ink causes orifices to be clogged and dust is deposited on the nozzle plate. As a result, it can be prevented that a dot dropout occurs during printing, reducing printing quality or disabling printing. With the closed cap system, however, since the chamber is sealed by mechanically pressing the nozzle plate of the jet nozzle against the cap, it is difficult to keep perfect sealing for a long period of time because of the existence of tiny foreign matters, flaws on surfaces of the nozzle plate, the deterioration of the elastic characteristics of the cap, change in a press state by travel of the recording head within a storage case, and the like. As a result, there is the problem that ink dries only a little over time, so that orifices are clogged. Also, if pressure within the chamber becomes high, since ink of the orifices returns to an ink tank, a dot dropout occurs, reducing printing quality or disabling printing.
As a system for solving the problem of the closed cap system, a system employing a cap having a air continuous hole is known. In a cap having the air continuous hole, since the difference of pressures inside and outside the chamber can be kept minimum by the air continuous hole providing communication between the chamber and the outside world, it can be prevented that ink within the orifices is pressed back to the ink tank. With the above system, however, since the air continuous hole provided on the cap causes ink to become drier, there is the problem that the orifices are clogged due to the dried ink in a shorter time than with the closed cap system.
Further improved systems are known; for example, the system of charging a cap with a liquid having the same component as ink and containing no color material, and the system of charging the cap with glycerin and diethylene glycol known as moisture retention materials. These systems prevent ink from drying by keeping the chamber under a saturated vapor pressure wherein the chamber is sealed or communicates partially with the air. These systems can solve the problem of ink being pressed by a change in pressure while preventing ink from drying for a longer period of time. However, since the liquid itself used evaporates and is lost over time, the liquid must be replenished as required to maintain the capability for a long period of time. Even in systems employing moisture retention materials relatively resistant to evaporation, it is difficult to prevent the loss of the liquid. In the above systems, as a liquid with which the cap is charged, one that is compatible with ink or has an affinity for the ink is used. Therefore, if ink within the orifices and the charged liquid contact each other, since a solution of two types of liquids or a mixed solution of them is produced, the characteristics of the ink are changed, making normal printing difficult. Moreover, a color material of the ink may mix with the liquid within the cap, causing color mixture.
The present invention has been made in view of the above circumstances and provides an ink drying prevention apparatus, an ink-jet recording head storage container, and an ink drying prevention method that can solve the above problems and prevent ink within an ink-jet recording head from drying for a long period of time. Also, the present invention provides an ink-jet recording apparatus that can prevent degradation in printing quality and disabled printing due to dried ink within an ink-jet recording head.
To solve the above problems, the present invention provides an ink drying prevention apparatus that prevents ink within an ink-jet recording head from drying, the ink drying prevention apparatus including a porous substance permeated with a seal liquid that is nonvolatile and incompatible with the ink within the head, wherein the porous substance can contact a nozzle surface of the ink-jet recording head.
In the ink drying prevention apparatus of the present invention, when the porous substance permeated with a seal liquid that is nonvolatile and incompatible with ink contacts on the nozzle surface of the ink-jet recording head, the seal liquid forms a large number of meniscuses of the seal liquid between the porous substance and the nozzle surface. As a result, a communication path between ink within a nozzle exposed to the nozzle surface and the outside world can be blocked. Since air gaps within the porous substance are charged with the seal liquid, a communication path in the porous substance in thickness direction is also completely blocked. Accordingly, ink within the nozzle is not exposed to the air around the recording head and nozzle clogging or solidification of the ink due to the drying can be relieved. Since the seal liquid is held within the porous substance by the capillary attraction of pores of the porous substance, it is not easily discharged to the outside and the ink drying prevention function can be maintained over a long period of time.
The present invention is an ink-jet recording head storage container provided with the ink drying prevention apparatus.
An ink-jet recording apparatus of the present invention includes an ink-jet recording head having the nozzle surface and the ink drying prevention apparatus supported so as to be contactable with the nozzle surface. The ink-jet recording apparatus may include a unit that, when ink is not jetted, brings the ink drying prevention apparatus into contact with the nozzle surface, and when ink is jetted, separates the ink drying prevention apparatus from the nozzle surface.
An ink drying prevention method of the present invention brings a porous substance permeated with a liquid that is nonvolatile and incompatible with ink, into contact with the nozzle surface of a recording head to prevent contact between the ink within the nozzle and the air, and prevents the ink within the ink-jet recording head from drying, wherein the seal liquid forms meniscuses between the porous substance and the nozzle surface.
In the ink drying prevention method, when the porous substance permeated with a seal liquid that is nonvolatile and incompatible with ink contacts on the nozzle surface of the ink-jet recording head, the seal liquid forms a large number of meniscuses of the seal liquid between the porous matte and the nozzle surface. As a result, a communication path between ink within a nozzle exposed to the nozzle surface and the outside world can be blocked. Since air gaps within the porous substance are charged with the seal liquid, a communication path in the porous substance in thickness direction is also completely blocked. Accordingly, ink within the nozzle is not exposed to the air around the recording head and nozzle clogging or solidification of the ink due to the drying of the ink can be relieved. Since the seal liquid is held within the porous substance by the capillary attraction of pores of the porous substance, it is not easily discharged to the outside and ink drying can be prevented over a long period of time.